[bug-66532] more performant way to iterate over codepoints. Thanks to Matthias Raschhofer

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1908458 13f79535-47bb-0310-9956-ffa450edef68

poi-ooxml/src/main/java/org/apache/poi/xssf/streaming/SheetDataWriter.java

@@ -31,6 +31,7 @@ import java.io.OutputStreamWriter;
 import java.io.Writer;
 import java.nio.charset.StandardCharsets;
 import java.util.Iterator;
+import java.util.PrimitiveIterator;
 
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
@@ -397,37 +398,39 @@ public class SheetDataWriter implements Closeable {
             return;
         }
 
-        for (Iterator<String> iter = CodepointsUtil.iteratorFor(s); iter.hasNext(); ) {
-            String codepoint = iter.next();
+        int codepoint;
+        for (PrimitiveIterator.OfInt iter = CodepointsUtil.primitiveIterator(s); iter.hasNext(); ) {
+            codepoint = iter.nextInt();
             switch (codepoint) {
-                case "<":
+                case '<':
                     _out.write("&lt;");
                     break;
-                case ">":
+                case '>':
                     _out.write("&gt;");
                     break;
-                case "&":
+                case '&':
                     _out.write("&amp;");
                     break;
-                case "\"":
+                case '\"':
                     _out.write("&quot;");
                     break;
                 // Special characters
-                case "\n":
+                case '\n':
                     _out.write("&#xa;");
                     break;
-                case "\r":
+                case '\r':
                     _out.write("&#xd;");
                     break;
-                case "\t":
+                case '\t':
                     _out.write("&#x9;");
                     break;
-                case "\u00A0": // NO-BREAK SPACE
+                case '\u00A0': // NO-BREAK SPACE
                     _out.write("&#xa0;");
                     break;
                 default:
-                    if (codepoint.length() == 1) {
-                        char c = codepoint.charAt(0);
+                    final char[] chars = Character.toChars(codepoint);
+                    if (chars.length == 1) {
+                        char c = chars[0];
                         // YK: XmlBeans silently replaces all ISO control characters ( < 32) with question marks.
                         // the same rule applies to "not a character" symbols.
                         if (replaceWithQuestionMark(c)) {
@@ -436,7 +439,7 @@ public class SheetDataWriter implements Closeable {
                             _out.write(c);
                         }
                     } else {
-                        _out.write(codepoint);
+                        _out.write(chars);
                     }
                     break;
             }

poi/src/main/java/org/apache/poi/util/CodepointsUtil.java

@@ -18,12 +18,28 @@
 package org.apache.poi.util;
 
 import java.util.Iterator;
+import java.util.PrimitiveIterator;
 
 @Internal
 public class CodepointsUtil {
+
+    /**
+     * @param text to iterate over
+     * @return iterator with Strings representing the codepoints
+     * @see #primitiveIterator(String) a more performnt iterator
+     */
     public static Iterator<String> iteratorFor(String text) {
         return text.codePoints()
                 .mapToObj(codePoint -> new String(Character.toChars(codePoint)))
                 .iterator();
     }
+
+    /**
+     * @param text to iterate over
+     * @return iterator with ints representing the codepoints
+     * @since POI 5.2.4
+     */
+    public static PrimitiveIterator.OfInt primitiveIterator(String text) {
+        return text.codePoints().iterator();
+    }
 }

poi/src/test/java/org/apache/poi/util/TestCodepointsUtil.java

@@ -23,6 +23,7 @@ import static org.junit.jupiter.api.Assertions.assertTrue;
 import java.util.ArrayList;
 import java.util.Iterator;
 import java.util.List;
+import java.util.function.IntConsumer;
 
 import org.junit.jupiter.api.Test;
 
@@ -38,8 +39,22 @@ class TestCodepointsUtil {
         List<String> codePoints = new ArrayList<>();
         CodepointsUtil.iteratorFor(unicodeSurrogates).forEachRemaining(codePoints::add);
         assertEquals(17, codePoints.size());
-        for(String point : codePoints){
-            assertTrue(point.length() >=1 && point.length() <= 2, "codepoint " + point + "is wrong size");
+        for (String point : codePoints) {
+            assertTrue(point.length() >= 1 && point.length() <= 2, "codepoint " + point + "is wrong size");
+        }
+    }
+
+    @Test
+    void testPrimitiveIterator() {
+        final String unicodeSurrogates = "\uD835\uDF4A\uD835\uDF4B\uD835\uDF4C\uD835\uDF4D\uD835\uDF4E"
+                + "abcdef123456";
+        List<String> codePoints = new ArrayList<>();
+        CodepointsUtil.primitiveIterator(unicodeSurrogates).forEachRemaining((IntConsumer) (i) -> {
+                    codePoints.add(new String(Character.toChars(i)));
+                });
+        assertEquals(17, codePoints.size());
+        for (String point : codePoints) {
+            assertTrue(point.length() >= 1 && point.length() <= 2, "codepoint " + point + "is wrong size");
         }
     }